A casting imperfection of TC10 alloy was treated by HIP process at 940∼950°C and at 120∼130MPa for 3∼3. 5h. Microstructure of the imperfections was analyzed. The closing interface still remained, which is black and incontinuous line-like. The black interface was observed by SEM-EDAX. Through comparing the composition between the cast and the interface, it was revealed that the black interface was not cavities enriched in impurities, but a nonuniformed interface of alloy elements. The results show that the closing mechanism of casting imperfections in HIP is a creeping and diffusion process. When the pressure is higher than the metal creeping strength at certain temperature, the imperfections are closed gradually. And the longer the holding time is, the better the closing results are.

A TC10 alloy casting with defect was treated by HIP process at 940-950°C and 120-130 MPa for 3-3.5 h. Microstructure of the defect was analyzed. Results show that the closing interface that is black and incontinuous line-like still remains. The black interface was observed by SEM-EDAX. Through comparing the composition between the matrix and the interface, it was revealed that the black interface was not cavities enriched in impurities, but a nonuniform interface of alloy elements. The analysis results show that the closing mechanism of casting defect in HIP is a creeping and diffusion process. When the pressure is higher than the metal creeping strength at a certain temperature, the defects are closed gradually. The longer the holding time is, the better the closing results are.